Marine LifeMarine Life

Classification and EvolutionClassification and Evolution

Big ConceptsBig Concepts -- Classification and Evolution•• Life on Earth has both great diversity and unityLife on Earth has both great diversity and unity

Diversity = Millions of different species of living organisms

Unity = All species share similar underlying materials, structures, and processes

•• Scientists use a natural classification system for living organismsScientists use a natural classification system for living organisms

Relies on evolutionary history and development characteristics

Based on common underlying natural origin that makes structural and evolutionary sense

Groups of organisms arranged systematically in a hierarchal set of categories = phylogeny

Each type of organism has a scientific name and is uniquely placed in the phylogeny

•• Classification of Organisms into a PhylogenyClassification of Organisms into a Phylogeny

Hierarchy includes Kingdom, Phylum, Class, Order, Family, Genus, Species

Each nested level of category indicates a certain degree of complexity, grade or class Each nested level of category indicates a certain degree of complexity, grade or class

Each category becomes more specific with every drop in level

This is the optimum type of classification system for the scientific study of marine life

•• Life on Earth has systematically changed over a great span of timeLife on Earth has systematically changed over a great span of time Life made its first humble appearance over 3 ½ billion years ago

Great explosion of most phyla occurred during the Cambrian Period over 500 MYA

A unique assemblage of species are found in the rock record for each time period

The order in which different major groups of organisms appear is unique

Every species appears on Earth at some point in time; most eventually go extinct

•• The Theory of Evolution is the best scientific explanation for changing LifeThe Theory of Evolution is the best scientific explanation for changing Life

Darwin’s Natural Selection = environment-controlled selection of fittest individuals

Genetic mutation = random development on new traits in offspring

Evolution in the marine environment highlighted by convergent evolution

The Scientific Classification of LifeThe Scientific Classification of Life

• Biologists classify organisms into various groupings in order to

better understand them.

• Taxonomy is the art or study of classification – placing

organisms into groups or taxa (taxon = singular)

• Modern organism taxonomy uses a tree (branching)-like

system of grouping, called a phylogeny.

• A phylogeny is the branching, hierarchal grouping or

arrangement of organisms that reflects organisms’ evolutionary

histories and ancestral relationships; closely related species

share a common ancestor (possibly now extinct)

• Various criteria used in classification include, genetics (DNA),

anatomy, behavior, life stage development, and cellular structure

Tree of Life Tree of Life

PhylogenyPhylogeny

• The phylogeny is a branching,

hierarchal grouping or

arrangement of organisms that

reflects organisms’ evolutionary

histories and ancestral

relationships; closely related

species share a common

ancestor (possibly now extinct)ancestor (possibly now extinct)

• Various criteria used in

classification include, genetics

(DNA), anatomy, behavior, life

stage development, and cellular

structure

• The base of the phyogeny is the

origin of life itself.

Life Life Domains Domains –– Base of the Tree of LifeBase of the Tree of Life

Three Life DomainsThree Life Domains

1)1) ArchaeaArchaea

2)2) BacteriaBacteria

3)3) EukaryotaEukaryota

Phylogenetic Tree of LifePhylogenetic Tree of Life

Based on Fossil Record and Modern-day Genetics

Understanding Phylogenies Understanding Phylogenies

Tree of Life PhylogenyTree of Life Phylogeny

Life Domains and Underlying KingdomsLife Domains and Underlying Kingdoms

Life’s Life’s Evolution & Evolution &

Diversification Diversification on on

EarthEarth1)1) Evolution of Prokaryote Evolution of Prokaryote

and and Eukaryote domainsEukaryote domains

2)2) Eukaryotes divided into Eukaryotes divided into

5 kingdoms5 kingdoms

3)3) Range of diversity Range of diversity 3)3) Range of diversity Range of diversity

indicated by indicated by line line

thickness thickness

4)4) Branches that don’t Branches that don’t

extend to top are extend to top are

extinct dead endsextinct dead ends

5)5) Uncertainties indicated Uncertainties indicated

by dashed by dashed lineslines

“Newer” “Newer”

Eukaryote Eukaryote

Treetop Treetop of of LifeLife1)1) A newer, more geneticallyA newer, more genetically--

accurate phylogeny of the accurate phylogeny of the

eukaryotes that does not use eukaryotes that does not use

“kingdoms” was proposed“kingdoms” was proposed

2)2) Eukaryotes divided into Eukaryotes divided into 7 7 2)2) Eukaryotes divided into Eukaryotes divided into 7 7

geneticallygenetically--tied “tied “SupergroupsSupergroups””

3)3) Tree shows both convergence Tree shows both convergence

and divergenceand divergence

4)4) Big part of evolution of singleBig part of evolution of single--

celled Eukaryotes involved celled Eukaryotes involved

organisms assimilating other organisms assimilating other

organisms into their cellsorganisms into their cells

Major Marine Life PhylaMajor Marine Life Phyla

InvertebratesInvertebrates

Phylum Porifera

Phylum Cnidaria

Phylum Ctenophora

Phylum Bryozoa

Phylum Brachiopoda

Phylum Mollusca

Kingdom Kingdom ProtistaProtista

MicroMicro--ProtistaProtista PhylaPhyla

Phylum Bacillariophyta

Kingdom Kingdom MoneraMoneraPhylum Bacterium

Archeabacteria

Eubacteria

Kingdom AnimaliaKingdom Animalia

Phylum Arthropoda

Phylum Echinodermata

Several Worm Phyla

VertebratesVertebratesClass Agnatha

Class Chondricthyes

Class Osteichthyes

Class Reptilia

Class Ave

Class Mammalia

Phylum Bacillariophyta

Diatoms

Phylum Sarcomastigophora

Dynaflagellates

Foraminifera

Radiolarians

MacroMacro--ProtistaProtista PhylaPhyla

Phylum Chlorophyta

Phylum Pheaophyta

Phylum Rhodophyta

Marine Plant PhylaMarine Plant PhylaMarine Plant PhylaMarine Plant PhylaMicroMicro--AlgaeAlgae

DiatomsDiatoms

CocolithophoresCocolithophores

DinoflagelletesDinoflagelletes

MacroMacro--AlgaeAlgae MacroMacro--AlgaeAlgae

KelpKelp

SeaweedSeaweed

Vascular PlantsVascular Plants

Sea GrassesSea Grasses

MangroveMangrove

Evolution of PhytoplanktonEvolution of PhytoplanktonEvolution of PhytoplanktonEvolution of Phytoplankton

Diatoms Cyanobacteria

Dinoflagelletes

Cocolithophores

Silicoflagelletes

Green Algae

Marine Marine Invertebrate AnimalsInvertebrate Animals

The Major Marine Invertebrate PhylaThe Major Marine Invertebrate Phyla1) Phylum Porifera = Sponges

2) Phylum Cnidaria = Jellyfish, Sea Anemone, and Coral

3) Phylum Ctenophora = Comb Jellies

4) Phylum Mollusca = Bivalves, Gastropods, and Cephalopods

Class Bivalves (clams, mussels, oysters, scallops.), Class Gastropods (snails, slugs, and

nudibrachs), and Class Cephalopods (squids, cuttlefish, octopusm, nautilus)

5) Phylum Arthropoda = Class Crustacea = Shrimp, Crabs, Lobsters, Krill,

Copepods, and BarnaclesCopepods, and Barnacles

6) Phylum Echinodermata = Sea Urchins, Sea Stars, Brittle Star, and Sea Cucumber

7) Phylum Bryozoa = Moss-like animals

8) Phylum Brachiopoda= Lamp-shelled animals

9) Phylum Annelida = Segmented worms (polychaetes)

10) Phylum Nematoda = Roundworms

11) Phylum Phoronida = Tube worms

12) Phylum Platyhelminthes = Flatworms

13) Subphylum Tunicata

– Sac-like, nano-corded

animal

Marine Marine Vertebrate AnimalsVertebrate Animals

Major Classes of Marine VertebratesMajor Classes of Marine Vertebrates

1) Class Agnatha = Jawless Fish

2) Class Chondrichthyes = Cartilaginous Fish (sharks, rays)

3) Class Osteichthyes = Bony or Ray-Fin Fish

Under Sub-Phylum Vertebrata

4) Class Reptilia = Marine Reptiles (turtles, lizards, snakes)

5) Class Aves = Marine Birds

6) Class Mammalia = Marine Mammals (whales, pinepeds)

Marine Vertebrate Marine Vertebrate PhylogenyPhylogeny1)1) Vertebrates came Vertebrates came

from an ancestral from an ancestral

chordate chordate

invertebrateinvertebrate

2)2) First vertebrates First vertebrates

were jawless fish were jawless fish

3)3) Jawed fish came Jawed fish came 3)3) Jawed fish came Jawed fish came

later later –– like sharks like sharks

and raysand rays

44) Bony) Bony--skeleton skeleton fish came even laterfish came even later

5) The 5) The tetrapodtetrapod vertebrates vertebrates (originally only the class of (originally only the class of

amphibians) amphibians) evolved from an evolved from an ancestral ancestral lobelobe--finned fishfinned fish

6) All 6) All marine marine tetrapodstetrapods evolved from ancestral landevolved from ancestral land--dwelling dwelling

forms, including the marine reptiles, birds, and mammals forms, including the marine reptiles, birds, and mammals

Vertebrate PhylogenyVertebrate Phylogeny

The Fish VertebratesThe Fish VertebratesThe Fish VertebratesThe Fish Vertebrates• Class Agnatha (jawless fish)

• Class Chondrichthyes (cartilaginous fish)

• Class Osteichthyes (bony fish)

These classes of Fish have several things in common:

1) Their earliest common ancestor lived in the early Paleozoic 1) Their earliest common ancestor lived in the early Paleozoic

2) They are all well-adapted to live in salt water

3) They all are interconnected in marine food webs

4) Most successful and longest-lived marine vertebrate

5) One or more of these classes found in every marine

ecosystem

6) Over 30,000 species of marine fishes

Fish Fish PhylogenyPhylogeny

Ostracoderms

Placoderms

Lampereys

Cartilaginous Fish

Bony Fish

Marine MammalsMarine MammalsMarine MammalsMarine Mammals1) Marine vertebrate animals that possess lungs for breathing, 1) Marine vertebrate animals that possess lungs for breathing, mammary glands for nursing and body hair; give birth to live mammary glands for nursing and body hair; give birth to live young; many have flippers for swimming; all are “warmyoung; many have flippers for swimming; all are “warm--blooded.”blooded.”

2) All marine mammals’ ancestors were originally land mammals 2) All marine mammals’ ancestors were originally land mammals that, over a long period of time, adapted to living in the oceanthat, over a long period of time, adapted to living in the ocean

3) There are about 110 species of marine mammals 3) There are about 110 species of marine mammals

4) Three taxonomic Orders of marine mammals:4) Three taxonomic Orders of marine mammals:

Order CetaceaOrder Cetacea ---- toothed and baleen whalestoothed and baleen whales

OrderOrder CarnivoraCarnivora -- Suborder PinnipediaSuborder Pinnipedia = (seals, sea lions, and walruses); = (seals, sea lions, and walruses); also the sea otters and polar bearalso the sea otters and polar bear

Order SireniaOrder Sirenia (manatees and dugongs)(manatees and dugongs)

5) Most marine mammals sit near the top of the food chain 5) Most marine mammals sit near the top of the food chain

except for the baleen whales and the sea cows.except for the baleen whales and the sea cows.

6) Most marine mammals face difficult environmental challenges6) Most marine mammals face difficult environmental challenges

Diversity of Marine Life Through TimeDiversity of Marine Life Through Time

Increasing Diversity Punctuated by

Mass Extinction Events

GLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTSGLOBAL MASS EXTINCTION EVENTS

Scientific Study of the History of LifeScientific Study of the History of Life

Science attempts to Science attempts to

explain nature using natural explain nature using natural

laws, forces, and processeslaws, forces, and processes

The Theory of Evolution The Theory of Evolution

is. by far, the best scientific is. by far, the best scientific

explanation explanation

The Theory of Evolution is The Theory of Evolution is

extremely wellextremely well--tested, and, tested, and,

broadly supported by a very broadly supported by a very

wide variety of robust wide variety of robust

physical evidencephysical evidence

Definition of Biological Evolution Definition of Biological Evolution

Evolution is the maintenance of life under changing conditions

by the continuous adaptation of successive generations of a

species to its environment

Biological evolution refers to populations and not to individuals

and that the changes must be passed on to the next generation.

Evolution is a process that results in heritable changes in a

population spread over many generations.

Evolution is any change in the frequency of alleles within a

gene pool from one generation to the next." - Helena Curtis and N.

Sue Barnes, Biology, 5th ed. 1989 Worth Publishers, p.974

New forms of life are derived from earlier forms of life

Incorrect Incorrect Definitions of Biological EvolutionDefinitions of Biological Evolution

“Evolution: The gradual process by which the present diversity

of plant and animal life arose from the earliest and most primitive

organisms, which is believed to have been continuing for the past

3000 million years." - Oxford Concise Science Dictionary

“Evolution: ...the doctrine according to which higher forms of

life have gradually arisen out of lower.." – Chambers

“Evolution: ...the development of a species, organism, or organ

from its original or primitive state to its present or specialized

state; phylogeny or ontogeny" - Webster's

Advanced forms of life are derived from primitive forms of life

Theory of Evolution and Natural SelectionTheory of Evolution and Natural Selection

Darwin’s and Wallace’s Ideas on Darwin’s and Wallace’s Ideas on HowHow life may life may

have changed through long spans of timehave changed through long spans of time

More offspring are produced than can survive to reproduce

Random variations occur in all organisms – some passable to

offspring

Meiosis

Mutations

Favorable inheritable traits increase the likelihood that the

organism will survive to reproduction age

Unfavorable traits decrease the likelihood that the organism

will survive to reproductive age

The organism’s natural environment itself does the selection

Darwin’s Finches

Theory of Evolution and Natural SelectionTheory of Evolution and Natural Selection

Darwin’s Finches as Explained by Natural Selection Darwin’s Finches as Explained by Natural Selection

Evolution = Evolution = SURVIVAL OF THE FIT ENOUGHSURVIVAL OF THE FIT ENOUGHSURVIVAL OF THE FIT ENOUGHSURVIVAL OF THE FIT ENOUGHSURVIVAL OF THE FIT ENOUGHSURVIVAL OF THE FIT ENOUGHSURVIVAL OF THE FIT ENOUGHSURVIVAL OF THE FIT ENOUGH

No biological predetermination = Purely a response to

environmental pressures

Accumulation of beneficial inherited structural or

behavioral traits = favorable adaptations

Organisms evolve to adequately fit their environment

Rates of change are variable, depending primarily on Rates of change are variable, depending primarily on

environmental stress, population size, and degree of

geographic isolation

Mass extinction events create extreme environmental

pressures on species

Big ConceptsBig Concepts -- Classification and Evolution•• Life on Earth has both great diversity and unityLife on Earth has both great diversity and unity

Diversity = Over 100 million different species of living organisms

Unity = All species share similar underlying materials, structures, and processes

•• Scientists use a natural classification system for living organismsScientists use a natural classification system for living organisms

Relies on evolutionary history and development characteristics

Based on common underlying natural origin that makes structural and evolutionary sense

Groups of organisms arranged systematically in a hierarchal set of categories = phylogeny

Each type of organism has a scientific name and is uniquely placed in the phylogeny

•• Classification of Organisms into a PhylogenyClassification of Organisms into a Phylogeny

Hierarchy includes Kingdom, Phylum, Class, Order, Family, Genus, Species

Each nested level of category indicates a certain degree of complexity, grade or class Each nested level of category indicates a certain degree of complexity, grade or class

Each category becomes more specific with every drop in level

This is the optimum type of classification system for the scientific study of marine life

•• Life on Earth has systematically changed over a great span of timeLife on Earth has systematically changed over a great span of time Life made its first humble appearance over 3 ½ billion years ago

Great explosion of most phyla occurred during the Cambrian Period over 500 MYA

A unique assemblage of species are found in the rock record for each time period

The order in which different major groups of organisms appear is unique

Every species appears on Earth at some point in time; most eventually go extinct

•• The Theory of Evolution is the best scientific explanation for changing LifeThe Theory of Evolution is the best scientific explanation for changing Life

Darwin’s Natural Selection = environment-controlled selection of fittest individuals

Genetic mutation = random development on new traits in offspring

Evolution in the marine environment highlighted by convergent evolution

DiscussionDiscussionDiscussionDiscussion

Conclusion: Conclusion: Life Life Changes Through TimeChanges Through Time